Although the genetic and molecular abnormalities of sickle cell disease have been well-established, there are still questions concerning sickle cell disease which cannot be explained by the well-known property of gel formation by deoxygenated sickle hemoglobin. The sequence of events leading to vasoocclusive crises has not been defined. This may be due to the lack of methods for detecting small molecular abnormalities than can also be used to study cellular and organ level events. The purpose of this research project is to investigate sickle cell disease at the molecular and cellular levels by using new biophysical techniques that are sensitive to very small conformational changes in the Hb S molecule yet will allow experiments with intact cells. These special techniques include the spin-label method, automatic continuous measurement of oxygen equilibrium curves of hemoglobin in solution and in erythrocytes, mechanical shaking method, a method for determining the amount of denatured hemoglobin in erythrocytes, and measurement of levels of glycolytic intermediates. The emphasis will be placed on investigating the properties of hemoglobin and erythrocytes in patients before, during and after crises with the goal of a better understanding of sickling disorders and the development of methods of detecting and preventing the onset of crises.